Soil isolation and molecular identification of Coccidioides immitis

The fungal pathogen Coccidioides immitis, causative agent of coccidioidomyc osis or Valley Fever; was first isolated from the environment in 1932. It h as been isolated on numerous occasions since then, but always with the use of a mammalian host. The morphology of C. immitis is indistinct from relate d species, thus, its identification hinges upon its ability to infect and p roduce spherules in a susceptible animal. In this study, four genetically d istinct isolates of C. immitis were isolated from soil samples from the San Joaquin Valley without the use of a host. None of these sites had been def initively associated with human infection. The isolates were identified fro m over 2400 soil isolates from 720 soil samples using C. immitis specific p rimers based on the ITS sequence of ribosomal DNR They were further typed u sing molecular markers available for clinical isolates of C. immitis.